Tube-type falling film evaporators are widely used for evaporation of liquid solutions. The liquid to be evaporated is fed to the inside of a plurality of tubes and is evaporated thereon by indirect contact with heating steam flowing in a space surrounding the outside of the tubes. During the process, a mixture of liquid and vapor exits from the lower end of the tubes with relatively high velocity which mixture must be then separated in the same manner as in a Kestner-type evaporator using a large receiving space located below the tube bundle. For reasons of economy, e.g. recovery of chemicals, and environmental concerns, care must be taken that drops of liquid are not carried along by the vapor leaving the evaporator.
One object of the present invention is to improve the separation of liquid and vapor in the evaporator, so that the vapor space of the evaporator can be more effectively utilized and consequently smaller vapor spaces for a specific duty can be designed than heretofore possible.